Reactions of 2,2ʹ,6ʹ,2ʹʹ-terpyridine and its complexes, with OH^• and e_aq^¯ - A radiolytic study

Abstract

The reactions of 2,2ʹ,6ʹ,2ʹʹ-terpyridine (terpy) and its complexes, Fe(terpy)₂²⁺ and Co(terpy)₂²⁺ have been studied under OH^•and e_aq^¯ conditions. The pulse radiolysis studies indicate formation of a transient, an adduct, with absorption maxima centered around 310 nm and 370 nm in the case of OH^•. In the case of e_aq^¯ reaction, <i>p</i>H dependent spectra have been obtained with absorption maxima around 310 nm and 390 nm at <i>p</i>H<i> </i>4.5 and a maximum around 325 nm at <i>p</i>H<i> </i>7.0. In this case an anion is formed on addition of e_aq^¯, which protonates immediately at the heterocyclic nitrogen, In the case of complexes, with both OH^• and e_aq^¯, ligand centered adducts are formed. All these adducts decay through a second order dimerization or disproportionation, a disproportionation reaction in the case of complexes.